Inlet ram for power plants



March 24, 1953 N.- c. PRICE INLET RAM FOR POWER PLANTS 3 Sheets-Sheet 1 Original Filed June 28, 1943 mmvron. NATHAN 0. PRICE Agent March 1953 N. c. PRICE INLET RAM FOR POWER PLANTS 3 Sheets-Sheet 2 INVENTOR.

NATHAN 0. PRICE Original Filed June 284, 1945 March 24, 1953 N. c. PRICE INLET RAM FOR POWER PLANTS Original Filed June 28, 1945 3 Sheets-Sheet 3 INVENTOR.

NATHAN C. PRICE Agent omm .F 00w .3 02502 uz a Patented Mar. 24, 1953 INLET RAM FOR POWER PLANTS Nathan C. Price, Los Angeles, Calif., assignor to Lockheed Aircraft Corporation, Burbank, Calif.

Original application June 28, 1943, Serial No.

492,647, now Patent No. 2,501,633, dated March 21, 1950. Divided and this application August 28, 1946, Serial No. 693,471

This invention is concerned with prime movers or power plants, and has more particular reference to the air inlet rams of power plants for propelling high velocity, high altitude aircraft,

11 Claims. (01. 6035.6)

of the present invention and showing the movable member of the ram inlet in its forward pofsition, the internal unit of the power plant appearing in side elevation;

etc. This application is a division of my copend- Figure 2 is a fragmentary longitudinal sectional ing application for United States Letters Patent, view of the forward portion of the plant illus- Serial No. 492,647, filed. June 28, 1943, now Pattrating the movable ram member in its rear poent No. 2,501,633, which is a continuation-in-part sition;

of my copending applications for United States Figure 3 is a front view of the power plant with Letters Patent, Serial No. 433,599, filed March certain parts broken away to appear in vertical 6, 1942, now Patent No. 2,540 991, and Serial No. cross section; 7

488,029, filed May 22,1943, now Patent No. 2,468,- Figure 4 is a fragmentary diagrammatic view 461. illustrating a hypothetical position of the mov- The air receiving or inducting inlet passages of able member when the airplane is static and with the power plants for high velocity and high altithe power plant in operation, with resultant typitude aircraft are utilized to effect a ramming cal entering air stream lines and isobaric flow or compression of the air. This is'particularly sections being indicated thereon; I important in the case of reactive propulsion en- Figure 5 iS a V ew e Figure 4 with e e gines which handle large volumes of air and comable member in actual rearward position while press the same before it is delivered to the heat the a p iS Static; and generator or hot gas generator. The present in- F gu es 6 and e m ar o Figure 4 u vention relates to the inlet rams for power plants trating the member in hypothetical rearward and of the reactive propulsion type and has for its actual forward positions respectively with the general object, the provision of a practical, efliairplane mov Y at a given V ycient device of this character. 33 The present invention is concerned primarily Another object of the invention is to provide with the inlet portion 01' ram Of a reactive p p an inlet ram incorporating means responsive to 81011 engineh s inlet 1 ram is Capable o 5 or influenced by an increase or decrease in the on power plants varying considerably in type, air speed of the power plant, a d aircraft with construction and operational speeds. However, which it is associated so as to automatically vary in Order t0 adequately disclose the ram means the effective area of the inlet passage. of the invention I have illustrated and described It is another object of the invention to provide the same in association with a power plant of an inlet ram of the character referred to wherein the kind disclosed in my aforementioned Patent the means for controlling the inlet passage in- No. 2,501,633. Itis to be understood that the cludes a member movable therein in response to 35, present invention is not confined in its applicathe aerodynamic conditions so as to be automatic tions to this particular engine or class of engine. in its operation. In the form of the invention For this reason, the details of the general power disclosed herein the passage-governing member plant are omitted from this disclosure and only is moved without the'necessity for providing the primary elements are shown and described special operating mechanisms, adjustments or 4-0 in order to disclose the principles of operation other devices for effecting its movement. of the invention.

A further object of the invention is to provide The power plant illustrated in Figure 1 inan inlet ram of the'class referred to wherein the eludes an internal unit In in the form of an movable member operates by axial movement in elongate assembly having an open forward end the ram to open, restrict and close an auxiliary for the reception of the rammed air and proor supplemental ram passage and thus vary the total effective area of the ram inlet in accordance with the different air speeds of the aircraft.

Other objects and features of the invention will be readily understood from the following detailed reactive type power plant embodying the features vided at its rear end with a discharge nozzle N.

The internal unit H] is in the nature of a hot gas generator or heat'generator, and in accordance with the disclosure in Patent No. 2,501,633, may comprise a turbine G and a combustion chamber portion Z, both in upstream relation to the nozzle N and compressor means C in upstream relation to the combustion chamber for supplying the same with air under pressure. The power plant further includes a diffuser envelope E spaced around and enclosing the internal hot gas generating unit ill. In the drawings, the envelope E is shown submerged or housed in the wing 70 of an airplane, or the like, it being understood that the power plant may be mounted in other manners. The envelope E is an elongate streamline shaped enclosure having a divergent inlet to be more fully described below, an intermediate section 42, and a rear convergent nozzle or discharge section 43. Spaced struts 53 and 54 support the forward and rearward portions of the heatgenera-tor unit :are bulb shaped in cross section and slidably en- IU in the envelope E so as tobe centrally orcoaxially positioned in the envelope. The envelope E has an outer skin H and an inner skin l2 with internal reiniorcinghoops Jor rings '13 arranged between the skins. "The inner'skin "i2 is spaced from the inner unit H to define or leave an annular air pa sage I4 leadingfrom the ram inlet to the discharge nozzle Q3. The rear chambered portion of the envelope E: is employed as'a-heat exchangerll. Pipes Hiand -15, and a pump-P-driven byva motor M circulatecooling fluid from the interior of the *hotgasgenerator ill throu h the heat exchanger space H. This fluid is directed through .a spiral passage Win .the heat exchanger-to flow in-indirect heat-exchange relation to the air traveling rearwardly throughthe pass-age M. "Counter rotating irnpellerblades -i9 are carried bv rotating-rings 2-8 which surround the internal unit 'LB'and'are driven by the turbine-G. The-blades l form a propulsive .blower in the-air passage 1-4. The structure thus zfare idescribed '-forms "a portion .of the-subject.matter-ofz-my-Patent No. 2,501,633.

The inlet-ram R of the-present invention 71S- characterized by -a-movable member :2! Tfor-varying the eflective area of :"the "ram' passage 22. The ram 1R. in'the particular application of the invention illustrated, is an annular :rearwardly divergent :forward portion of the envelope E. The rammed air inlet passage 22 may be some- :what restricted-in diameter in the region of the struts 53, there being anannular 'concavityin theupassage between'its iforwa'rd lip "and the struts. The *rampassage'22 again flares or 'diverges "rearwardlyifrom the "restriction adj acent thefstruts. The movable member "2'! -for vary- .ingithe efi'ective area ofithe inle'tram 'R is shown tozbein-the'formof a tubularior annular part defining a rearwardly divergent rop ening or pasisage 24. The wall "of this'passage 2 4 is con- 'toure'd :so ast'c ."form a forward extension of the internal wall-of the above describedainpassage 14 with the member either in the forward posi- .tionpf Figure 1 or in the rearward'p'ositionei Figure'z. The :member :2! is substantially air- "foil shape-din cross section, and. has aforward portion which is externallyenlarged-or-rsome- This portion or increased wall what. bulbous. thickness is preferably hollowed onchambered out ito'reduce the weight. The member '2! is proportionedzso that'it is free "to' move axially'in the ram'R with desirable slight clearance. As shown in :FigureZ, themernber '2! is-capable of moving rearwardly a considerable :distance to :have' itsv trailing edge'rearwardly of the struts53.

gaged in'correspondingly shaped channels 21 in the enlarged 'forward portion of the ram member 2!. The guide rods carry the member 2| .icrifreeaxial movement in the ram R.

With the movable inlet member 2! in the forwardjposition shown in Figure 1, it serves to reduce the efiective area of the ram passage, its 'forwa'rdiportion operating to close off the annular space or passage P which surrounds the member. On the other hand, when the member 2! is in the rearward position of Figure 2, this auxiliary or supplementalpassageaP is open-for the reception oframmed air and there .isasub- .stantialz-increase in the total effective cross sectional area of the inlet opening. At relatively lowaair speeds, for-example, speeds under approximately JZGO feet-per second. the member 2! assumes a rearward p osition'such as shown in Figure 2,.being urged rearwardlwby the drag of the enteringair. In this position, the ram R has-a-maximum opening area-for the induction of-themaximum volumeof :rammed air. .This rammed air is supplied to the internal heat generating unit H] and the passage l4. As the velocity of the :power plant increases, the ,pres- .sure of the rammediairaincreases inthe forward portion of the envelope E byth-e difiuser'action, andithis increased-pressure acting on the rearwardly directed internal and external surfaces of the member -2I --moves the member forwardly against the drag of the entering air. The member 1.21 automatically :moves forwardly at the higher :air speeds to assume a position where :it restrictsor substantially-closes-the outer or=supplemental rampassagefiP-to reduce the eflective area of the ram :R. -:During opera-tionof the power plant, themembe-r -Z'I will automatically assume a position to -control thevolume' oi the rammed air received or inducted by the/engine substantially in proportion toits airspeed. =The movable :member :21 responding'to -the aerodynamic conditions :at the :ram :R consitutes an automatic "control'or governor "element iforthe rammed rairisupply "inducted into the-"power .plant.

Figures .4, "5,"6iand :7 diagrammatically :illus- .trate different positions, both hypothetical and :actual, of the movable member 2! .under conditions wvhere the airplane is static and -moving -:forwardl-y at a given velocity. In the descriptionito followit will-bewapparent that the member 2 I under given rconditions, will assume "the actual position *and "cannot assume the-hypo 'theticalposition due to; air'forces acting thereupon. :In each of these figures it is assumed thatthe power; plant .is iii-operation at rated rotativezspeed ahd' that the design flow'velocity of the air entering the ducted blading i9 is there for approximatelyconstant. atavalued 350 feet per second'forexample. The lines 50 in-Figures 4,?5; 6- and 7 illustrate the typical stream lines of the air entering thepower plant inlet ram.

The'znotation-s A and :B'signify the margins of undisturbed flowoutside inside of themember 2l ,j respectively. The notation N signifies .thesirmargin rof the orb". of Ifree; air necessary .to

supply the rated volumetric flow to the ducted compressor at the assumed airplane forward speed. It will be assumed that the airplane is operating at sea level altitude, it being understood that although the forces acting upon the movable member vary in magnitude in the same ratio as the altitude density, these proportional forces do not change direction with altitude. In accordance with the streamlines 40, the broken lines 4! in Figures 4, 5, 6 and 7 indicate cross sectional flow areas of constant pressure extending from chosen points or lines on the surface of the member 2! where the pressures may be determined by applying Bernoulli's and the Continuity equations for flow of elastic fluid, as is customary in the solution of problems involving flow of elastic fluid through passages of varying cross section. The resulting values are thereafter integrated to obtain the net induced axial forces acting upon the member 2!. These isobaric flow sections indicated by the lines 4| are designated 0, 4, 3, 2, I, T, l, 2', 3, 4, l3, 4", 3" and 4". Assuming the conditions of altitude, ambient temperature and the design air flow velocity (approximately 350 feet per second) entering the ducted blading I9, to be constant and uniform in the four conditions of operation illustrated in Figures 4, 5, 6 and 7 and employing Bernoullis equation with the method of energies disclosed 6-44, Navships 250-330-6 of the United States Navy Department, the induced forces acting on the member 2! in the conditions illustrated diagrammatically in Figures 4, 5, 6 and '7 are approximately as follows. and to these forces are added skin friction forces customarily obtained by the fanning friction equation, to obtain the net force.

(1) Hypothetical condition of Figure 4 where in Memorandum Number:

the airplane is static and member 2! is assumed P 1 to be in a forward position1230 pounds induced force acting in the rearward direction, plus 49 pounds skin friction force rearward, making a total force rearward of 1279 pounds.

(2) Actual condition of Figure 5 where the airplane is static and member 28 is in a rearward position56 pounds induced force acting in the forward direction combined with 91 pounds skin friction force rearward, making a net force rearward of 35 pounds.

(3) Hypothetical condition of Figure 6 where the airplane ,is moving forwardly at approximately 600 feet per second and where the member 2| is assumed to be in a rearward positionl400 pounds induced force acting in the forward direction, minus 168 pounds skin friction force rearward, making a net force forward of 1232 pounds.

(4.) Actual condition of Figure '7 where the airplane is moving forwardly at aproximately600 feet per second and where the member 2! is in the forward position-2560 pounds induced force acting in the forward direction minus 172 pounds skin friction force rearward, making a net force of 2388 pounds.

The above enumerated induced forces acting axially upon the member 2! are derived by integration of the air pressure forces in pounds per square foot imposed on the surfaces of the. member 2| at the isobaric flow sections desighated by the lines 4!, with respect to the ring areas of the member 2| projected in a forward or rearward direction as applicable.

(1) Condition illustrated in Fi ure 4 in which the absolute positive pressure acting on the for- 1 ward facing portion of the member 2| dominates, pushing the member rearward.

Flow sections 0 4 3 2 1 Lb. per sq. ft.

prcssure. .2ll5 Flow sections 4 Lb. per sq. ft.

pressure i055 1975 (2) Condition illustrated in Figure 5 in which the fore and aft induced axial pressures acting on the member 2| approximately balance, but in which the friction drag force dominates holding the member in rearward position.

Flow sections 0 4 3 2 1 '1 l 2 3 Lb. per sq. ft.

pressure l940 1930 1900 2000 1930 1880 1925 1980 2010 Flow sections. 4 0 4 3 4 Lb. per sq. ft.

pressure "2040 2030 2040 1875 1940 (3) Condition illustrated in Figure 6 in which suction force acting on the forward facing portion of the member dominates, tending to draw the member forward.

Flow sections 0 4 3 2 1 Lb. per sq. ft.

pressure 2100 2005 2155 Flow sections" 4 0' 4 Lb. per sq. ft.

pressure "2500 2430 2345 1030 2070 (4) Condition illustrated in Figure 7 in which suction force acting on the forward facing and outer portion of the member is intensified by external air flow, increasing the force to hold the member forward.

Flow seotions 0 4 3 2 1 1' 2' 3 Lb. per sq. ft.

pressure 1030 1020 1910 2120 1220 1500 1209 2120 2250 Flow sections" 4 0' Lb. per sq. it.

pressure.. -.2340 2370 'r l 2' a Ill 1/ 2! 3! From the foregoing it will be seen that the movable member 2| will be moved or forced rearwardly when the airplane is static, thereby increasing the effective area of the inlet (Figures 4 and 5) and improving the efiiciency of the ducted compressor flow system. However, the member 2! cannot remain in a rearward position when the forward velocity of the airplane is substantial (Figure 6) and has a strong force acting forwardly upon it to hold it in a forward position when the airplane forward speed is substantial. Under the condition of substantial forward speed, the efficiency of air diffusion is improved and external draglosses are reduced-as will be seen by comparison of Figures 6 and 7.

Having described only a typical form of the invention, I do not wish to be limited to the specific details herein set forth, but wish to. reserve to myself any variations or modifications that may appear to those skilled in the art and/ or fall within the scope of the following claims.

I claim:

1. An air induction device for a power plant comprising an air conduit having a ram inlet at its forward end, the passage in the inlet being rearwardly divergent, and means for controlling the inlet including an airfoil shaped annular member movable between a rearward position where it is spaced from the wall of the inlet to leave an annular passage for the induction of air and a forward position where it cooperates with the divergent inlet to close said annular passage and thus reduce the effective air receiving area of the inlet, the chord of the airfoil member being substantially parallel with the longitudinal axis of the inlet the member presenting surfaces acted upon the aerodynamic pressures in the inlet to cause movement between said positions, the inlet being unobstructed except for said member.

aiaircraftpropelling power plant, a dir fuser having a ram inlet at its forward end, and a member, operated solely by aerodynamic means, mounted in said inlet to slide freely axially thereof under air pressure, said member having an air passage extending therethrough from one end thereof to the other, said ram inlet having a portion divergent relative to the outside surface of said member whereby an air passage is providedbetween said inlet and said member that varies in area as said member moves axially in said inlet, said member having at least one surface facing rearwardly and exposed to air pressure generated in said diffuser.

3. An air induction device for a power plant of the character described comprising an openended air conduit having a ram inlet and a diffuser'at its forward end, and means for controlling; the inlet including" an annular member, opened at both ends and operated solely by aerodynamic means, mounted in said inlet to be freely slidable axially therein under air pressure, said-member having a surface exposed to incoming air and having a rearwardly facing surface exposed to said diffuser and to air pressure generated therein so that said air pressure may tend to force said member forwardly against the action of the aerodynamic drag of the incoming air, said ram inlet having a portion that is rearwardly divergent relative to the outside surface of said member, whereby an annular'air passage is provided between said inlet and said member that varies in area as said member is moved axially in said inlet.

4. An air induction device for a power plant of the character described comprising an air conduit having" a ram inlet and diffuser at its forward end and means for controlling the inlet comprising" an annular member, opened at both ends and o erated Sblely by aerodynamic means,

of airfoil shape in axial section movable axially in the inlet, said member having a surface exposed to incoming air and having a rearvvardly facing internal surface exposed to pressure generated in the diffuser; whereby said member is urged forwardly against the action of the aerodynamic dragof the incoming air, said ram inlet having a rearwardly divergent portion providing an annular air passage between said inlet and said member that varies in area as said member is movedaxially in said inlet.

5. Ari-air induction device for a power plant of the character described comprisingan air condiiit' having a ram inlet and a diffuser at its forward end and means for controlling the inlet comprising an annular member, opened at both ends and operated solely by aerodynamic means, of airfoil shape in axial section-movable axially in the inlet, and means for guiding said member iii-its axial movement in said inlet, said member having a front face exposed to incoming air and havinginternal and rearwardly facing surfaces exposed to the pressure generated in the difiuser, said ram inlet having a rearwardly divergent portionprovidin-g an-annular air passage between said inlet and saidmember that varies in area as said member is moved axially insaid inlet.-

7 6.- An air induction device for a power plant of the character described comprising an air conduit having aranrinlet at its forward end-and'a diffuser behind said inlet, and means for controlling said inlet including an annular member, openedsatboth ends-and operated solely by aerodynamic'means, mountedcoaxially of said inlet to be freely slidable therein, said member having a ated solely by aerodynamic means, mounted in said inlet, said inlet having a restriction therein, and one ofsaid parts being movable longitudinally relative to theother t control the effective cross=sectional area of said ram inlet, said mov able part being elongated in longitudinal section and arranged with its longitudinal axis substantially parallel with the axis of said inlet, saidon'e movable part-having a forward end surface facing in the upstream direction to be acted upon by the axial aerodynamic forces of the air flow into the ram inlet and having surfaces facing in part inthe downstream direction to be acted upon by the induced pressures of the air flowing through the ram inlet, and means for su port ing and guiding said movable part for free slid"- ing movement axially of said inlet through the sole operation of air pressure on said forwardly and rearwardl-y fading surfaces of said movable part.

8. In a power plant of thechara'ete'r described, a diffuser having a divergeutram inlet at its forward end, an annular member, opened at both ends and operated solely by" aerodynamic means, movable axially in the'inlet to control the effec' tive area theredf, said member having elongate axial section and having its axis extend ng substantially parallel Withthe axis of said inlet, said member having a forward end surface exposed to andacted upon-by the axial aerodynamic forces of the air flow intosaid inlet, and said member having internal and external surfaces facing in the rearward direction t6 be exposed to and acted upon the-air'pressure' in the d-iifuser, and means for supporting and guiding said memberfor free sliding movement axially of said inlet between a forward po'si on Where it restricts the effective size of said inlet and a, rearward position where theeffective size of said inlet is increased.

9 Ida power'plant ofthe characterdescribed a diffuser having a divergent ram inlet at i-ts for ward end, annular 'mnieber, opened at both ends and operated solely by aerodynamic means, movable axially inthe inlet to control tl'ie' effective" area thereof, said member having an elo1i= gate axial section and having its axis extending substantially parallel'ivith the axis of said inlet, mean's supporting said member for free axial movement in the inlet'betweena rearward-position, where it restricts the inlet to a minimum extent, anda forward position, Where it restricts the inlet toa maximum extent, said member having a forward end surface exposed to and acted upon by" the air flowing into the inlet, and said member having rearwardly facing external and internalsurfaces exposed to and acted upon by the pressures in said diffuser.

1-0; An inlet ram forpower plants comprising a rearwardly divergent stationary annular ram, a movable annularmember substantially airfoilshaped in cross: sectionlocated Within said ram, said ramhaving a forward lip portion and an inner surfacebeing annularly' relieved immediately beyond said lip portion to provide a supplemental passage between said movable annular member and said ram, struts perpendicularly connected to said ram, axially aligned guide rods secured to said lip and said struts, said movable annular member having channels for slidable engagement with said guide rods and slots at the trailing edge adapted to receive said struts upon rearward travel of said member, said movable annular member having a bulbous leading edge and a trailing edge curved slightly toward said ram, whereby said movable annular member when in forward position shuts off the supplemental passage, the outer surface of said bulbous leading edge closely approaching the forward lip portion of said ram, and the curved trailing edge of said annular movable member closely approaching the restricted portion of said ram.

11. An inlet ram for power plants comprising a rearwardly divergent stationary annular ram, a hollow movable annular member substantially airfoil-shaped in cross section located within said ram, said ram having a forward lip portion and an inner surface being annularly relieved immediately beyond said lip portion to provide a supplemental passage between said movable annular member and said ram, struts perpendicularly connected to said ram, axially aligned guide rods secured to said lip and said struts, said movable annular member having channels for slidable engagement with said guide rods and slots at the trailing edge adapted to receive said struts upon rearward travel of said member, said ram being restricted in diameter in the region of said struts and relieved immediately beyond said restriction, said movable annular member having a bulbous leading edge and a trailing edge curved slightly toward said ram, whereby said movable annular member when in forward position shuts off the supplemental passage, the outer surface of said bulbous leading edge closely approaching the forward lip portion of said ram, and the curved trailing edge of said annular movable member closely approaching the restricted portion of said ram.

NATHAN C. PRICE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS (Addition to Patent No. 779,655) 

